return to its original position.

"You have probably seen toy ones; a heavy lead wheel inside a ring.
When the wheel is spinning that, and the ring in which it is
contained, may be placed in almost any position, on a very slender
support and they will remain stable, or at rest.

"So I put a gyroscope on my airship, and I found that it kept the
machine in a state of equilibrium no matter what position we were
forced to take by reason of adverse currents. Of course it was not
an entire success, but I was coming to that.

"In the biplane which was wrecked in the river I had my latest
gyroscope. It seemed to be perfect, and, with Jack and Harry, I
had made a number of beautiful flights. I even flew alone upside
down, and had no trouble.

"Before that I had made the acquaintance of Lieutenant Larson, who
is also an expert aviator. He worked for me before he went in the
army. He had his own ideas about equilibrium, and his plan, which
he wanted me to adopt, consists of tubes of mercury that can
automatically be tilted at different angles. I do not believe they
will ever work, and I told him so. I refused to use them, and he
and I parted, not the best of friends. He wanted his invention
exploited, but I refused to try it, as I thought it dangerous.

"When my gyroscope worked fairly well, I presume Lieutenant Larson
was professionally jealous. At any rate he, left me, and I am glad
of it."